Each day, tens of thousands of patients go through inpatient and outpatient procedures resulting in either biopsies or excised tissues. These biological samples are often used for diagnostic evaluation to determine the present of disease and to determine the appropriate treatment for the disease or research. Tissue samples obtained from a patient for molecular diagnostic and analysis, such as RNA, DNA, and protein analysis, which have become commonplace in research for the treatment of disease require quality, intact nucleic acids.
A biopsy sample or tissue is typically sectioned using cryostatic sections, as is known in the art, or processed and embedded in paraffin blocks to facilitate cutting of pathological slides used in diagnostic and research applications. In order to facilitate visualizing these biopsies by microscopic examination, the cells/tissue must first be processed and embedded in a carrier medium to allow cutting after paraffin embedding. After the specimen has been collected, the tissue sample is preserved by passing it through fixatives to remove water from the sample, and then processed with a solvent to dissolve fatty materials and “clear” the tissue sample. After being “cleared”, the tissue sample is placed in molten paraffin and it is infiltrated with the wax, which replaces the solvent which will evaporate or be diluted to trace levels, causing all the tissue to be infiltrated with a common wax binder. The sample may then be cut in a section plane to be presented to the microtome blade for creation of a microscope slide, which may be examined microscopically for information collection. The paraffin wax capsules which form the specimen samples are cast is small containers called “boats”, or in two-piece containers such as those described in McCormick (U.S. Pat. No. 2,996,762). A microtome is used to section the embedded tissue, which are mounted on a substrate, like a histology slide, for staining or further analysis, and subsequent histological characterization. The remainder of the embedded tissue specimen is stored for future use and reference.
A variety of automated systems have been developed for use in histology laboratories for labeling slides prior to mounting specimens to the slides. Many of the systems focus on labeling the slide with specific information, such as patient information and tissue type or a printed bar code which may be scanned to obtain the patient database records. For example, Carls, et al. (U.S. Pat. No. 3,733,768) describes a histology specimen tray with rows of compartments for storing specimens using wax to fix the specimens into place.
These blocks and slides are soon thereafter manually filed and archived into one of several plastic, metal, or cardboard filing/storage systems. As a general rule of policy and law, the blocks and slides are retained for as many as 10 years or longer. Systems are known that permit processing of tissue samples, such as those described in McCormick (U.S. application Ser. No. 12/425,583). During this filing process the blocks, which have a wax/paraffin media can be damaged. The blocks can be scratched, gouged, dislodged from the parent cassette, or even melted, if the temperature of the storage location is too hot. In addition, other hazards of storage may arise with long-term conditions. These may include, but are not limited to, insect damage, rodent threat and damage, and dirt and debris in the storage location.
Later, when the block is needed for additional staining or review purposes, the block will be handled again and subjected to the same handling/storage conditions. Normally, the administrative person pulling the block will leave a tag indicating that the block has been removed and for whom the block was pulled (the requesting pathologist's name). This is supposed to give a tracking aspect to the storage system. However, as human nature would allow, this seldom is achieved and blocks go unaccounted for and then time is wasted tracking down the person or office which now possesses the block. In addition, current storage systems tightly store the histology sample paraffin blocks, to save on storage space. As a consequence of this tight fit, if the person does place a “pulled” tag in the area, most of the time the tag gets pulled away by constant opening and closing of the tray/drawer. The same holds true for the pathology slides which were created from the parent block.
Therefore, the art is underdeveloped for long-term paraffin block storage which allows easy identification of the sample, sample location, and safe storage conditions.